Gill is a town in Franklin County, Massachusetts, United States. The population was 1,551 at the 2020 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area. The campus of Northfield Mount Hermon School is located in the Mount Hermon section of the town. By sheer coincidence, "Gill" is the only full municipality of the 351 towns and cities currently administered in the Commonwealth of Massachusetts whose name has characters entirely in alphabetical order.